Conversions
Volume converter
Convert volume measurements from cubic metres into common metric and imperial units.
Calculators / Construction / Concrete volume
Concrete volume calculator
Estimate concrete volume with a waste allowance.
On this page
Volume including allowance1.65m³
Net slab volume1.5m³
Calculator controls
How to calculate
Estimate concrete volume with a waste allowance.
Volume = length × width × depth ÷ 100; order volume = volume × (1 + waste ÷ 100)
Worked example
Length (m): 5; Width (m): 3; Depth (cm): 10; Waste allowance (%): 10.
Volume including allowance: 1.65 m³; Net slab volume: 1.5 m³.
Assumptions and limits
Rectangular slab only. Confirm structural specifications and supplier order quantities separately.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Net slab volume uses the slab’s dimensions. The allowance increases the amount to account for your chosen margin above the geometric estimate.
When this tool is useful
Estimate material volume for a rectangular slab before confirming an order with a supplier.
Understanding your inputs
| Input | What to enter |
|---|---|
| Length (m) | Enter a number of at least 0.001 and no more than 1000000000000. |
| Width (m) | Enter a number of at least 0.001 and no more than 1000000000000. |
| Depth (cm) | Enter a number of at least 0.001 and no more than 1000000000000. |
| Waste allowance (%) | Enter a number of at least 0 and no more than 100. |
Frequently asked questions
Is the allowance a structural safety factor?
No. It is a quantity allowance. This calculator does not design reinforcement or verify structural adequacy.
Does it calculate cement bags?
No. Bag yield depends on the product and mix. Check the manufacturer’s volume yield.